Ciaccio P J, Stuart J E, Tew K D
Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Mol Pharmacol. 1993 Jun;43(6):845-53.
We report the initial identification of a 37.5-kDa putative aldoketo reductase in human colon carcinoma cells. An aminoterminal trypsin fragment was sequenced and found to be identical to bovine prostaglandin F synthase in 19 of 21 amino acids. Levels of this cytosolic human aldo-keto reductase, assessed by immunoblots using polyclonal antibodies raised against this protein, increased 30-fold in cells resistant to the Michael reaction acceptor ethacrynic acid and increased with time and ethacrynic acid concentration after treatment of wild-type cells. Induction of the reductase appeared to be cell type and drug specific. It was induced by the Michael reaction acceptors dimethyl maleate, t-butylhydroquinone, and hydroquinone but not by the nitrogen mustard chlorambucil. Ethacrynic acid and dimethyl maleate induced the reductase in a second human colon cell line but not in human prostate cells. NADPH-dependent metabolism of aldoketo reductase substrates by cytosol from colon but not prostate cells was enhanced 2-3-fold when cells were grown in the presence of either ethacrynic acid or dimethyl maleate. The discrepancy between induced reductase activity and protein levels may be due to the multiplicity of constitutively expressed NADPH-dependent reductases that compete for substrate. Ethacrynic acid-resistant cells exhibited low levels of cross-resistance to Adriamycin, mitomycin C, and the bovine prostaglandin F synthase substrates phenylglyoxal and prostaglandin D2. Thus, significant overexpression of a human aldo-keto reductase structurally related to bovine prostaglandin F synthase may result from exposure of cells to Michael reaction acceptors and may give rise to an enhanced capacity to metabolize exogenous and endogenous substrates, thereby contributing to the drug-resistant phenotype.
我们报道了在人结肠癌细胞中首次鉴定出一种37.5 kDa的假定醛酮还原酶。对其氨基末端胰蛋白酶片段进行测序，发现其21个氨基酸中有19个与牛前列腺素F合酶相同。使用针对该蛋白产生的多克隆抗体通过免疫印迹评估这种胞质人醛酮还原酶的水平，在对迈克尔反应受体依他尼酸耐药的细胞中增加了30倍，并且在野生型细胞经依他尼酸处理后随时间和依他尼酸浓度增加。还原酶的诱导似乎具有细胞类型和药物特异性。它由迈克尔反应受体马来酸二甲酯、叔丁基对苯二酚和对苯二酚诱导，但不由氮芥苯丁酸氮芥诱导。依他尼酸和马来酸二甲酯在第二个人结肠细胞系中诱导了还原酶，但在人前列腺细胞中未诱导。当细胞在依他尼酸或马来酸二甲酯存在下生长时，结肠细胞而非前列腺细胞的胞质溶胶对醛酮还原酶底物的NADPH依赖性代谢增强了2 - 3倍。诱导的还原酶活性与蛋白质水平之间的差异可能是由于组成性表达的竞争底物的NADPH依赖性还原酶的多样性。依他尼酸耐药细胞对阿霉素、丝裂霉素C以及牛前列腺素F合酶底物苯乙二醛和前列腺素D2表现出低水平的交叉耐药性。因此，与人前列腺素F合酶结构相关的人醛酮还原酶的显著过表达可能是细胞暴露于迈克尔反应受体的结果，并且可能导致代谢外源性和内源性底物的能力增强，从而导致耐药表型。
